This invention has to do with swimming pool filters, and more particularly with a valve structure useful in controlling modes of use of a swimming pool filter.
Swimming pools contain tens of thousands of gallons of water which must be chemically treated and repeatedly filtered to maintain a healthful, attractive condition. For this purpose, variations of swimming pool filters have been devised, including most popularly tank-type filters which contain a regenerable filtering medium either of the fixed or removable bed type. In each type of filter, swimming pool water is passed, under pressure, through the filtering medium, the contaminants are separated therefrom, and the water, now filtered, is returned to the swimming pool. The accumulation of contaminants, typically particulate and oily matter, progressively blocks water passages through the filtering medium and ultimately requires replacement of the filtering medium or renewal thereof. For economy's sake, regenerable filters which may be repetitively renewed are preferred. In such filters, the filtering medium may typically be a bed of sand or a layer of diatomacious earth or the like which is interposed between the inlet and the outlet of the filter for the purpose of trapping particulate or oily contaminants from the swimming pool water being passed therethrough. Upon a sufficient accumulation of such contaminants, the filtering medium "channels" giving non-filtering passage to swimming pool water and/or the pressure within the tank increases to the limit of the pump being used to force water through the filter, as it becomes progressively more difficult for water to find its way through the gelatinous mass of accumulated contamination. The extent of contaminant accumulation may be readily measured by gauging the pressure drop across the filter, which at a given point is a signal that the filter is no longer functioning effectively or that the pump being used to move the pool water is insufficient to effect further movement against the pressure drop experienced across the filtering medium in the filter tank.
At this point, the pool owner needs to regenerate his filtering medium. For this purpose, it is conventional to reverse the flow of water through the filtering medium, whereby the pool water is directed in such a manner that the accumulated contaminants are flushed free of the filtering medium, and, hopefully with as little loss as possible of filtering medium, the contaminants are flushed from the filter tank. Generally, the flushed contaminants are directed to a "waste" line for disposal beyond the pool. After thus "backwashing" the filtering medium, the filter is again connected in the conventional mode and filtration of pool water resumed.
Increasing sophistication of pool owners and rising expectations of equipment performance have dictated refinements in the basic swimming pool filter just described. For example, it has been observed that the reconnection of a swimming pool filter in the filtration mode following a backwash operation results in a discharge of residual contaminant-containing water back into the pool, to the owner's dismay. There has been suggested the use of a "rinse" mode to obviate the problem. In a rinse mode, the swimming pool is connected as for filtration; that is, the pump inlet passes the water through the filtering medium as during filtration, but the outlet from the filter tank is not to the pool, but is again to the waste line until the residual contamination has been completely flushed from the filtering system. It is further sometimes desired by pool owners to have a highly forceful, if unfiltered, flow of water for therapy pools, or spas, as they are called. In such operation modes, swimming pool water is passed through the filter tank but not through the filtering medium, and thus is discharged from the filter tank with virtually full pump force. This mode of operation of the filter is often termed a "recirculation" mode.
Naturally, in each of these modes it is necessary to close off alternate tank connections. In order to provide multi-modal use of the swimming pool filters there have been devised a number of multi-port valves which have settings appropriate to several or all of the foregoing modes of operation of a filter tank.